System and Method for Using an Electronic Expansion Valve to Control a Discharge Pressure in a Multi-Purpose HVAC System

ABSTRACT

A method for using an electronic expansion device in a system for heating water and conditioning an interior space by operating a first controller to monitor the operating discharge pressure from the compressor; and operating the first controller to produce a signal designating expansion of an orifice within the electronic expansion valve when the operating discharge pressure is greater than or equal to a predetermined pressure value.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to, and claims the priority benefitof, U.S. Provisional Patent Application Ser. No. 61/869,017 filed Aug.22, 2013, the contents of which are hereby incorporated in theirentirety into the present disclosure

TECHNICAL FIELD OF THE DISCLOSED EMBODIMENTS

The presently disclosed embodiments generally relate to systems forheating water and conditioning an interior space, and more particularly,to a system and method for using an electronic expansion valve tocontrol a discharge pressure in a multi-purpose heating, ventilation,and air-conditioning (HVAC) system.

BACKGROUND OF THE DISCLOSED EMBODIMENTS

A typical water heater for residential hot water production and storageis an electrical resistance water heater and storage tank, although gaswater heaters are also used to heat water in a storage tank. Waterheaters typically include a storage tank defining a chamber forretention of water. A water inlet pipe is provided with a firstconnection for interconnection with a cold water supply line thatconveys fresh, relatively cold water into the storage tank. In the caseof electrical resistance water heaters, there are electrical resistanceelements, within the storage tank, that heat the water.

An alternative method for heating water is an active desuperheater waterheater. In one example of an active desuperheater water heater, theactive desuperheater water heater uses a small pump to circulate waterfrom a water storage tank, through a heat exchanger, and back into thewater storage tank. The active desuperheater water heater intercepts thesuperheated hot gas that is rejected from an air conditioner or heatpump compressor, sitting outside the home, and transfers the heat to thewater circulating through the heat exchanger. The active desuperheaterwater heater works only when the air conditioner or heat pump isoperating in a cooling mode.

Another alternative method for heating water is a heat pump waterheater. A heat pump water heater contains a fan, compressor, and anevaporator configured to sit on top of the water storage tank. The heatpump water heater circulates a refrigerant through an evaporator andcompressor, and uses a fan and evaporator to pull heat from airsurrounding the heat pump water heater in order to heat the refrigerant.The heated refrigerant runs through a condenser coil within the waterstorage tank, transferring heat to the water stored therein.

Yet another alternative method for heating water is a HVAC systemcoupled with a water heater module to form a multi-purpose system. Thismulti-purpose system utilizes a water heater module to divert arefrigerant to an indoor unit assembly when conditioning an interiorspace, or to the water heater module's heat exchanger when heatingwater. The outdoor heat pump circulates a refrigerant through anevaporator and compressor, and uses a fan and the evaporator to pullheat from air surrounding the heat pump in order to heat therefrigerant. The heated refrigerant runs through the water heater moduleheat exchanger, transferring heat to water also circulating through thewater heater module heat exchanger.

During water heating operation, the operating discharge pressure withinthe outdoor heat pump may increase to levels that make the water heatingcycle inefficient at a minimum, or may cease operation of the system.Generally, to control the discharge pressure, a thermostatic expansionvalve is used to regulate the refrigerant flow into the evaporator.Generally, the function of the thermostatic expansion valve is to hold aconstant evaporator superheat. When set and operating properly, thethermostatic expansion valve will keep the evaporator active throughoutits entire length. However, use of a thermostatic expansion valve in amulti-purpose system requires use of additional valves to relievepressure throughout the system for optimal performance. Therefore, thereis a need for a method to use an expansion device to control theoperating discharge pressure in a multi-purpose HVAC system to increaseoptimal performance.

SUMMARY OF THE DISCLOSED EMBODIMENTS

In one aspect, a method for using an electronic expansion device tocontrol an operating discharge pressure in a multi-purpose HVAC systemis provided. In one embodiment, the method includes the step ofoperating the multi-purpose HVAC system in a water heating mode. In oneembodiment, the multi-purpose HVAC system includes an outdoor unitassembly including a compressor, a first controller and an electronicexpansion device, operably coupled to a water heater module, the waterheater module including at least one valve. In one embodiment, the atleast one valve includes a pair of three way valves. In one embodiment,the multi-purpose HVAC system is configured to circulate a refrigerantfrom the outdoor unit assembly through the water heater module, andreturn to the outdoor unit assembly. In one embodiment, operating themulti-purpose HVAC system in a water heating mode generally includesoperating one or more of the at least one valves to configure arefrigerant circuit. For example, a refrigerant circuit is generallyconfigured by a second controller commanding one or more of the at leastone valves to be placed in an open state, and commanding one or more ofthe at least one valves to be placed in a closed state.

The method includes the step of operating the first controller tomonitor the operating discharge pressure from the compressor. The methodincludes the step of operating the first controller to produce a signaldesignating expansion of an orifice within the electronic expansiondevice when the operating discharge pressure is greater than or equal toa predetermined pressure value.

In one embodiment, the method includes the step of operating the firstcontroller to remove the signal designating expansion of the orificewithin the electronic expansion device when the operating dischargepressure is less than the predetermined pressure value. In anotherembodiment, the first controller removes the signal designatingexpansion of the orifice within the electronic expansion device when themulti-purpose HVAC system stops operating in the water heating mode. Inanother embodiment, the first controller removes the signal designatingexpansion of the orifice within the electronic expansion device when theorifice reaches a maximum opening size.

In one aspect, a multi-purpose HVAC system for heating water andconditioning an interior space is provided. In one embodiment, themulti-purpose HVAC system includes an outdoor unit assembly including acompressor, a first controller, and an electric expansion device, anindoor unit assembly, a water heater module including, at least onevalve and a second controller, a plurality of conduits fluidicallycoupling the water heater module to the outdoor unit assembly and theindoor unit assembly. The second controller is configured to operate theoutdoor unit assembly and the water heater module in a water heatingmode. In one embodiment, the second controller is configured to operatethe at least one valve to configure at least one refrigerant circuit. Inone embodiment, the at least one valve includes a pair of three wayvalves.

In one embodiment, the at least one valve includes a first valve, afirst conduit coupling the first valve to an inlet of the heatexchanger, a second valve, a second conduit coupling the second valve toan outlet of the heat exchanger, a third valve, a third conduit couplingthe third valve to the first valve, a fourth valve, a fourth conduitcoupling the fourth valve to the second valve, wherein the secondcontroller is configured to open the first and second valves and closethe third and fourth valves to configure the refrigerant circuit.

In one embodiment, the first controller is configured to monitor theoperating discharge pressure from the compressor. In one embodiment, thefirst controller is configure to produce a signal designating expansionof an orifice within the electronic expansion valve when the operatingdischarge pressure is greater than or equal to a predetermined pressurevalue.

In one embodiment, the first controller is configured to remove thesignal designating expansion of the orifice within the electronicexpansion valve when the operating discharge pressure is less than thepredetermined pressure value. In another embodiment, the firstcontroller is configured to remove the signal designating expansion ofthe orifice within the electronic expansion device when themulti-purpose HVAC system stops operating in the water heating mode. Inanother embodiment, the first controller is configured to remove thesignal designating expansion of the orifice within the electronicexpansion device when the orifice reaches a maximum opening size.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments and other features, advantages and disclosures containedherein, and the manner of attaining them, will become apparent and thepresent disclosure will be better understood by reference to thefollowing description of various exemplary embodiments of the presentdisclosure taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a system for heating water andconditioning an interior space in one embodiment;

FIG. 2 is a method for using an electronic expansion device to control adischarge pressure in a system for heating water and conditioning aninterior space in an exemplary embodiment;

FIG. 3 is a method for using an electronic expansion device to control adischarge pressure in a system for heating water and conditioning aninterior space in an exemplary embodiment; and

FIG. 4 is a method for using an electronic expansion device to control adischarge pressure in a system for heating water and conditioning aninterior space in an exemplary embodiment.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of this disclosure is thereby intended.

FIG. 1 illustrates a multi-purpose system for heating water andconditioning an interior space, utilizing an embodiment of the presentdisclosure, and indicated generally at 10. Particularly, themulti-purpose system 10 includes a water heater module 12 operablycoupled to an outdoor unit assembly 14 and an indoor unit assembly 16.

In one embodiment, outdoor unit assembly 14 includes a heat exchanger18, a compressor 20, a fan 22, a first controller 24, and an electronicexpansion device 26 including an orifice (not shown). The firstcontroller 24 is in electrically coupled to the compressor 20, fan 224,and the electronic expansion device 26 for control thereof. The firstcontroller 24 provides the outdoor unit assembly 14 with a variety ofoperation modes and control sequences to execute instructions during oneof a heating mode and a cooling mode. Outdoor unit assemblies 14include, but are not limited to air-to-air or ground source heat pumps.The electronic expansion device 26 is fluidically coupled to an outdoorunit assembly return connector 28 via a conduit 30. The electronicexpansion device 26 generally controls the amount of refrigerant flowinto the heat exchanger 18, thereby controlling the superheating at theoutlet of the heat exchanger 18. Outdoor unit assembly 14 is fluidicallycoupled to the outdoor unit assembly supply connector 32 via a conduit34.

In one embodiment, water heater module 12 includes a heat exchanger 36configured to allow a refrigerant to circulate therethrough. It will beappreciated that the heat exchanger 36 may be external of the waterheater module 12. The water heater module 12 includes a plurality ofvalves 38A-D configured to direct the flow of the refrigeranttherethrough. The refrigerant supply side inlet of heat exchanger 36 iscoupled to valve 38A via a conduit 40. The refrigerant return sideoutlet of heat exchanger 36 is coupled to valve 38C via a conduit 42. Avalve 38B is coupled to valve 38A via a conduit 44. A valve 38D iscoupled to valve 38C via a conduit 46. The valves 38A and 38B arefurther coupled to an outdoor unit assembly supply connector 48 via aconduit 50. Valve 38B is further coupled to an indoor unit assemblysupply connector 52 via a conduit 54. It will be appreciated that thevalves 38A and 38B, together with the conduits 44, 50 and 54, functionas a first three-way valve. The valves 38C and 38D are further coupledto the outdoor unit assembly return connector 28 via a conduit 56. Valve38D is further coupled to an indoor unit assembly return connector 58via a conduit 60. It will be appreciated that the valves 38C and 38D,together with the conduits 46, 56, and 60 function as a second three-wayvalve.

In one embodiment, water heater module 12 further includes a water pump62 to draw water therein. Water pump 62 is coupled to a water supplyconnector 64 via a conduit 66. Water pump 62 is further coupled to heatexchanger 36 via a conduit 68. The water heater module 12 includes awater return connector 70, which is coupled to heat exchanger 16 via aconduit 72.

A second controller 74 is in electrical communication with each of theplurality of valves 38A-D and the water pump 62 for control thereof. Thesecond controller 74 provides the water heater module 12 with a varietyof operation modes and control sequences to execute instructions duringone of an interior space conditioning mode and water heating mode.

Indoor unit assembly 16 includes a heat exchanger 76, an expansiondevice 78, and an indoor fan 80. Indoor unit assemblies 16 include, butare not limited to air handlers. Indoor unit assembly 16 is fluidicallycoupled to the indoor unit assembly return connector 58 via a conduit 82and fluidically coupled to the indoor unit assembly supply connector 52via a conduit 84.

Water heater module 12 is in electrical communication with outdoor unitassembly 14 and indoor unit assembly 16 via a wired or wirelessconnection (not shown). Water heater module 12 generally operates toswitch outdoor unit assembly 14 and indoor unit assembly 16 between aninterior space conditioning mode and a water heating mode.

A water storage tank such as the tank 86 is configured to produce asignal to indicate when a water heating mode should be initiated. Waterstorage tank 86 is fluidically coupled to the water supply connector 64via a conduit 88 and fluidically coupled to the water return connector70 via a conduit 90. During a demand to heat water, water storage tank86 is configured to send a signal to water heater module 12 to operatein a water heating mode. During use, water exits water storage tank 86via domestic supply line 92, and returns via domestic return line 94.

FIG. 2 illustrates an exemplary method 100 for using an electronicexpansion device 26 to control a discharge pressure in a multi-purposesystem 10 for heating water and conditioning an interior space. Method100 includes the step 102 of operating the multi-purpose system 10 in awater heating mode. In one embodiment, the multi-purpose system 10generally operates in a water heating mode by operating one or more ofthe at least one valves 38A-D to configure at least one refrigerantcircuit. For example, the at least one refrigerant circuit may beconfigured by the second controller 74 commanding valves 38A and 38C tobe placed in an open state, and commanding valves 38B and 38D to beplaced in a closed state. In one embodiment, outdoor unit assembly 14 isconfigured to circulate a refrigerant from the compressor 20 and intoconduit 34. The refrigerant generally enters the water heater module 12through outdoor unit assembly supply connector 48, wherein therefrigerant is directed through valve 38A and circulates through heatexchanger supply conduit 40. The refrigerant generally circulatesthrough heat exchanger 36 and exits heat exchanger 36 via heat exchangerreturn conduit 42. The refrigerant is generally directed through valve38C, and exits through outdoor unit assembly return connector 28. Therefrigerant generally returns to outdoor unit assembly 14 via conduit 30and through the electronic expansion device 26 and through heatexchanger 18. The refrigerant will continue to circulate through the atleast one refrigerant circuit until the water heating demand issatisfied.

Step 104 includes operating the first controller 24 to monitor theoperating discharge pressure from the compressor 20. The compressedrefrigerant exits the compressor 20 at an operating discharge pressure.Over time, the operating discharge pressure may increase due tooperating conditions. The first controller 24 determines the orifice(not shown) size setting of the electronic expansion device 26 basedupon the outdoor ambient temperature and the orifice is held at thatsize until the operating discharge pressure reaches a predeterminedpressure value set below a maximum safe pressure for the compressor 52.

If the operating discharge pressure is greater than or equal to thepredetermined pressure value, as shown in step 106, the method continuesto step 108, which comprises operating the first controller 24 toproduce a signal designating expansion of the orifice within theelectronic expansion device 26. Generally, to expand an orifice withinthe electronic expansion device 26, the first controller 24 produces asignal that is applied to a motor (not shown) within the electronicexpansion device 26, wherein the motor is used to open and close theorifice In some embodiments, the motor rotates a fraction of arevolution for each signal sent by the first controller 24. Expandingthe orifice within the electronic expansion device 26 allows morerefrigerant to pass therethrough, thus, lowering the operating dischargepressure of the compressor 20.

In one embodiment, as shown in step 110, if the operating dischargepressure is less than the predetermined pressure value, the methodcontinues to step 112, which comprises operating the first controller 24to remove the signal designating expansion of the orifice within theelectronic expansion device 26 so that the orifice size will be held atthis position.

In another embodiment, as shown in FIG. 3, step 110 is replaced withstep 110A, which determines if the multi-purpose HVAC system 10 hasstopped operating in the water heating mode. If so, the first controller24 removes the signal designating expansion of the orifice within theelectronic expansion device 26 in step 112. When the multi-purpose HVACsystem 10 stops operating in the water heating mode, the flow ofrefrigerant from the outdoor unit assembly 14 to the water heater module12 is reduced, thus, lowering the operating discharge pressure of thecompressor 20.

In another embodiment, as shown in FIG. 4, step 110 is replaced withstep 110B, which determines whether the orifice has reached a maximumopening size. If so, the first controller 24 removes the signaldesignating expansion of the orifice within the electronic expansiondevice 26 in step 112. It will be appreciated that the first controller24 and the second controller 74 may be combined into one controller.

It will be appreciated that the electronic expansion device 26 canexpand the orifice therein to regulate the discharge pressure from thecompressor 20 to keep the multi-purpose HVAC system 10 operating withoutthe need for additional pressure relief devices.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain embodiments have been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A method for using an electronic expansion deviceto control an operating discharge pressure in a multi-purpose HVACsystem including an outdoor unit assembly, the outdoor unit assemblyincluding an electronic expansion valve, a compressor and a firstcontroller, operably coupled to a water heater module, the water heatermodule including at least one valve, the multi-purpose HVAC systemfurther, the method comprising the steps of: (a) operating themulti-purpose HVAC system in a water heating mode; (b) operating thefirst controller to monitor the operating discharge pressure from thecompressor; and (c) operating the first controller to produce a signaldesignating expansion of an orifice within the electronic expansionvalve when the operating discharge pressure is greater than or equal toa predetermined pressure value.
 2. The method of claim 1, furthercomprising: (d) operating the first controller to remove the signaldesignating expansion of the orifice within the electronic expansionvalve when the operating discharge pressure is less than thepredetermined pressure value.
 3. The method of claim 1, furthercomprising: (d) operating the first controller to remove the signaldesignating expansion of the orifice within the electronic expansionvalve when the multi-purpose HVAC system stops operating in a waterheating mode.
 4. The method of claim 1, further comprising: (d)operating the first controller to remove the signal designatingexpansion of the orifice within the electronic expansion valve when theorifice reaches a maximum opening size.
 5. The method of claim 1,wherein the at least one valve comprises a pair of three way valves. 6.The method of claim 1, wherein step (a) comprises a second controlleroperating one or more of the at least one valves to configure at leastone refrigerant circuit.
 7. The method of claim 6, wherein the at leastone valve comprises: a first valve coupled to an inlet of a heatexchanger via a first conduit; a second valve coupled to an outlet ofthe heat exchanger via a second conduit; a third valve coupled to thefirst valve via a third conduit; a fourth valve coupled to the secondvalve via a fourth conduit; wherein step (a) comprises opening the firstand second valves and closing the third and fourth valves.
 8. The methodof claim 6, wherein the at least one refrigerant circuit circulates arefrigerant from the outdoor unit assembly, through the water heatermodule, and returns to the outdoor unit assembly.
 9. A multi-purposeHVAC system comprising an outdoor unit assembly including a firstcontroller, a compressor, and an electronic expansion valve; an indoorunit assembly; a water heater module including at least one valve, aheat exchanger, and a second controller; and a plurality of conduitsoperatively coupling the water heater module to the outdoor unitassembly and the indoor unit assembly; wherein the first controller isconfigured to: (a) operate the multi-purpose HVAC system in a waterheating mode; (b) monitor the operating discharge pressure from thecompressor; and (c) produce a signal designating expansion of an orificewithin the electronic expansion valve when the operating dischargepressure is greater than or equal to a predetermined pressure value. 10.The multi-purpose HVAC system of claim 9, wherein the at least one valvecomprises a pair of three way valves.
 11. The multi-purpose HVAC systemof claim 9, wherein step (a) comprises the second controller operatingone or more of the at least one valves to configure at least onerefrigerant circuit to circulate a refrigerant from the outdoor unitassembly through the water heater module, and returns to the outdoorunit assembly.
 12. The multi-purpose HVAC system of claim 11, whereinthe at least one valve comprises: a first valve; a first conduitcoupling the first valve to an inlet of the heat exchanger; a secondvalve; a second conduit coupling the second valve to an outlet of theheat exchanger; a third valve; a third conduit coupling the third valveto the first valve; a fourth valve; a fourth conduit coupling the fourthvalve to the second valve; wherein the second controller is configuredto open the first and second valves and close the third and fourthvalves to configure the at least one refrigerant circuit.
 13. Themulti-purpose HVAC system of claim 9, wherein the first controller isconfigured to remove the signal designating expansion of the orificewithin the electronic expansion valve when the operating dischargepressure is less than the predetermined pressure value.
 14. Themulti-purpose HVAC system of claim 9, wherein the first controller isconfigured to remove the signal designating expansion of the orificewithin the electronic expansion valve when the multi-purpose HVAC systemstops operating in a water heating mode.
 15. The multi-purpose HVACsystem of claim 9, wherein the first controller is configured to removethe signal designating expansion of the orifice within the electronicexpansion valve when the orifice reaches its maximum opening size.